The present invention relates to a new rasp blade for use in tire buffing machines. More particularly, the present invention relates to a tire rasp blade having a new and unique configuration to permit its more effective and safe assembly into the conventional rasp hub of a tire buffing machine.
Tire buffing machines are well known in the tire retreading industry. Conventionally, a tire buffing machine includes both a structure for mounting a used tire and a rasp hub which removes the worn tread from the used tire prior to the retreading process. The used tire is rotated while it is held against the rapidly rotating rasp hub whose outside perimeter is provided with a multitude of tire rasp blades. When so engaged against the used tire, the blades cut or shear small segments of rubber from the worn tread surface area of the tire. In this way, the tire is "buffed" to remove the unwanted used tread and to achieve an evenly textured surface suitable for retreading.
Tire rasp blades, together with intervening spacers, are assembled on the periphery of the rasp hub between the hub front and back plates. U.S. Pat. Nos. 2,703,446 and 4,019,234 disclose such conventional prior art rasp hub assemblies wherein the back plate of the hub has axially directed support pins on which are mounted the rasp blades and spacers. The front plate is then disposed onto the support pins against the assembled blades and spacers and locked into place. The disclosures of U.S. Pat. Nos. 2,703,446 and 4,019,234 are incorporated herein by reference.
While these prior art tire buffing machine hub assemblies have proven generally satisfactory, they nevertheless suffer certain disadvantages. For example, because the blades and spacers are always mounted to the hub in coextensive, side-by-side alignment, the blades and spacers are not interlocked around the circumference of the hub. Thus, a failure of any pair of support pins can result in a catastrophic hub failure. Moreover, the use of conventionally aligned spacers and blades produces undesirable lines in the buffed tire surface. These lines reduce the uniformity of texture on the buffed surface and may lead to premature retread failure.
Therefore, a need exists for a more effective and safer rasp hub assembly.